Poor adherence, inadequate drug levels, prior existing drug resistance or inadequate potency of the drugs chosen can all contribute to ARV treatment failure. Treatment failure is considered as either clinical failure, immunological failure or virological failure.

Clinical failure :

It is defined as recurrent, persistent or new HIV related illness after at least 3 months on ART. Also lack or decline of growth rate, development of encephalopathy or neuroregression is taken as clinical failure. Symptoms of opportunistic infections occurring in the first 3 months of ART concurrent with a rapid rise of CD4 values is termed as immune reconstitution syndrome (IRIS) and is not failure of ART. Pulmonary tuberculosis alone is not indicative of treatment failure and thus does not necessitate change is second line therapy.

Immunological failure :

Failure to increase age related CD4 threshold despite an adequate trial of ART.

Developing or returning to the following age-related immunological thresholds after at least 24 weeks on ART, in a treatment-adherent child: CD4 count of ≤200 cells/mm3 or %CD4+ ≤10% for a child more than 2 years to less than 5 years of age and CD4 count of ≤100 cells/mm3 for a child 5 years of age or more.

Virologic failure :

Repeated detection of virus in plasma after initial suppression to undetectable levels. (Ensure that increase is not due to infection, vaccination or problems with test methodology. Increase should be at least 3 fold from lowest viral load level).